Document collating apparatus

ABSTRACT

An apparatus for collating sheets, the apparatus comprising: a collating station having a collating position limited at its downstream end by a stop member against which the sheets abut whilst they are being collated; means for conveying sheets to the collating position so as to form a collated sheet set comprising a predetermined number of stacked sheets; a collating station eject device for moving the collated sheet set away from the collating position to an exit position; and means for conveying the collated sheet set from the exit position out of the apparatus to a downstream sheet handling device; wherein the collating station eject device comprises at least one movable pawl arranged to push each collated sheet set away from the collating position to the exit position and wherein the apparatus is adapted to collate a second sheet set at least partially overlying the first sheet set.

The present invention relates to apparatus and a method for collatingdocuments, for example for accumulating documents or sheets of paper forbulk mailings, such as when more than one sheet of paper is to be mailedin the same envelope.

In recent years there has been a trend to design systems, particularlylarger systems, as a set of modules which can be linked together toperform a complex process. There are several advantages to designingsystems in a modular form, for example it provides the ability tocustomise the system for the users' requirements by adding or removingfeatures, and permits the changing of individual modules for repair orupgrade.

A typical mailing system, such as the Automailer 5 Plus™ manufactured byPFE International Limited, comprises multiple modules including a modulefor inserting paper into the system, a printing module, a cuttingmodule, a collate module, a folding module, and a module for insertingthe documents into envelopes.

In an optimal modular mailing system each module would be able toreceive the output from the upstream module as soon as it is madeavailable, and provide input to the downstream module as soon as thedownstream module is ready to receive. In reality however optimalperformance is rarely possible due to a number of factors including thevarying complexity of each module, the physical limitations of thetechnology used, and bottlenecks, delays or blockages in a module.

A simple collate module receives individual sheets of paper and stacksthe sheets one by one in a collate pocket until a sheet set is complete.However, the collate module cannot transport the set from the collatepocket to the module output, until a downstream module, such as a foldermodule, is ready to accept the set.

Thus an inherent problem of a simple collator is that it is not possibleto start collating a second set until the first set is transported outof the collate pocket to a downstream module. This can cause a delay inthe system when the downstream module is not able to receive the sheetset as soon as it completed, for example if there is a blockagedownstream.

When this occurs the completed sheet set must wait in the collate pocketuntil the downstream module is able to accept the set, and in themeantime the collate module is unable to begin collation of a secondsheet set. Further delay occurs if the downstream device is ready toaccept the second sheet set before the collate module has finishedcollating the second set.

U.S. Pat. No. 5,083,769A addresses this problem using a dual collatingmachine having two separate collate pockets for collating sheet sets.Once a sheet set is completed in the first pocket, the apparatus divertsthe incoming sheets belonging to the next set to a second pocket,allowing the second set to be collated before and/or during thetransportation of the first set to the downstream device. Whilst such amachine reduces the delay in collating sets, the hardware required is ineffect two separate collate modules in parallel, with additionalhardware for diverting the incoming sheets and outgoing sets. Not onlyis such a machine more expensive to produce, but it is also a physicallylarger machine than a single collator. The dimensions, and in particularthe footprint of the machine is important, especially in modular systemswhere it is usually a requirement that the module fits into thepredetermined space available for the module.

According to a first aspect of the present invention there is providedan apparatus for collating sheets, the apparatus comprising: a collatingstation having a collating position limited at its downstream end by astop member against which the sheets abut whilst they are beingcollated, means for conveying sheets to the collating position so as toform a collated sheet set comprising a predetermined number of stackedsheets; a collating station eject device for moving the collated sheetset away from the collating position to an exit position; means forconveying the collated sheet set from the exit position out of theapparatus to a downstream sheet handling device; wherein the collatingstation eject device comprises at least one movable pawl arranged topush each collated sheet set away from the collating position to theexit position and wherein the apparatus is adapted to collate a secondsheet set at least partially overlying the first sheet set.

Thus the present invention allows for the collation of a second sheetset to begin before the first sheet set has left the collator, withoutincreasing the footprint of the collator.

The invention allows the transportation out of the collating module of afirst sheet set to be delayed without slowing or interrupting theaccumulation of a second sheet set.

Thus downstream delays or blockages can be accommodated without slowingdown the overall processing speed.

According to a preferred embodiment of the invention the collatingstation eject device and the exit conveying means are operableindependently of each other. The exit conveying means preferablycomprises a pair of holding rollers.

The pawl may be mounted on an outer surface of a belt which may be anendless belt driven cyclically.

The apparatus preferably comprises two pawls mounted at generallyequidistantly spaced intervals on the belt.

The stop member is preferably spring loaded and the location of the stopmember and the collating station eject device is advantageouslyadjustable depending on the length of the sheets to be collated.

In a preferred embodiment sensors may be arranged to detect the presenceof a sheet at the collating position and/or at the holding rollers.

A scanner may be arranged to read machine control data printed on sheetsentering the apparatus. This may be a bar code scanner, and OCR reader,a magnetic reader or any other reading device, e.g. for 2D data matrixmarks, a camera and computer may be used to read marks. Alternativelydata may be input directly to the system.

One or more hold points may be provided upstream of the collatingstation.

According to a second aspect of the present invention there is provideda method for collating sheets comprising: conveying sheets to acollating position in a collating station so as to form a collated sheetset comprising a predetermined number of stacked sheets; ejecting thecollated sheet set from the collating position by using a pawl to pushit away from the collating position to an exit position; at leastbeginning to form a second collated sheet set in the collating positionpartially overlapping the first sheet set in the exit position; andsubsequently conveying the first collated sheet set out of the exitposition to a sheet handling device downstream of the apparatus when thedownstream device is ready.

Preferably the movement of sheet sets from the collating position to theexit position is independent of the movement of sheet sets from the exitposition.

The method may also comprise sensing when a sheet is present at thecollating position.

To accommodate different sizes of sheets, the collating position ismovable relative to the exit position which may be defined by a pair ofholding rollers.

Sensors are advantageously provided to detect the presence or absence ofsheets at various positions in the path of the apparatus and if delaysoccur then the sheets will be held at suitable hold points. The sheetsmay also be scanned for machine control data prior to transportation tothe collating station.

For a better understanding of the present invention, and to show how thesame may be carried into effect, reference will now be made, by way ofexample, to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a known apparatus for collatingsheets;

FIG. 2 is a cross-sectional view of an apparatus according to thepresent invention;

FIG. 3 is a cross-sectional view of part of the apparatus of FIG. 2.

FIG. 1 shows a known apparatus for collating sheets. A sheet feeder 1 isarranged to deliver sheets of paper one by one, in the direction ofarrow F, to a collator 2. A barcode scanner 3 is positioned to scan eachsheet as they travel from the feeder 1 to the collator 2. This reads abarcode on each sheet which determines the number of sheets to becollated together, for example the number of sheets in a bank statementfor a particular recipient. Each sheet is transported along the collator2 by frictional contact between an upper conveyor transport belt 4 and alower conveyor transport belt 5 which are driven by an input conveyordrive 6. Downstream of the feeder 1 a first hold point sensor 7 isarranged to identify the presence and/or absence of a sheet at a pointon the conveyor 5 and a first hold point drive 8 controls thetransportation of sheets to a first hold point 9 downstream of the firsthold point sensor 7. Similarly, there is a second hold point sensor 10,a second hold point drive 11 and a second hold point 12 downstream ofthe first hold point 9. A collate pocket 13 is provided downstream ofthe second hold point 12 which comprises a collate pocket stop 14against which sheets can be collated one on top of each other, and acollate pocket sensor 15 for detecting the presence and/or absence ofsheets in the collate pocket 13. An output conveyor transport belt 16driven by an output conveyor drive 17 is arranged to transport thecollated sheet set passed a movable bounce stop 18 to a pair of outputrollers 19, which are in turn arranged to deliver each collated sheetset to a downstream device for further processing, for example forfolding and/or insertion into an envelope. An output sensor 20 isprovided to identify the presence and/or absence of a sheet set at theoutput of the collator 2.

A sheet set can comprise any number of sheets and each consecutive sheetset can comprise the same or a different number of sheets. To aidunderstanding, the operation of the apparatus will now be describedusing the example of collating two 3-sheet sets, the sheets beinglabelled sheet A1, A2, A3 and B1, B2, B3.

Sheet A1 is held at the output of the feeder 1 until the first holdpoint sensor 7 indicates that there is no earlier sheet blocking thedownstream path. Sheet A1 is then transported by the conveyor transportbelts 4, 5 to the first hold point 9. Prior to arriving at the firsthold point 9, sheet A1 is scanned for machine control data by thebarcode reader 3. This scanning process identifies which sheet set sheetA1 belongs to, and in particular is used to identify the first and/orlast sheet in a sheet set.

The second hold point sensor 10 is then checked and if there is noearlier sheet blocking the downstream path sheet A1 is transported tothe second hold point 12. At substantially the same time the first holdpoint sensor 9 is also checked and if the path is clear sheet A2 isscanned by the barcode reader 3 and transported from the feeder 1 to thefirst hold point 9.

The purpose of the two hold points 9, 12 is to maintain only a minimaldistance between the consecutive sheets in the collator 2 thus speedingup the sheet flow.

Since sheet A1 has been identified by the barcode reader 3 as the firstsheet in a set, the collate pocket sensor 15 is checked to ensure thatno earlier sheets are present in the collate pocket 13. If an earliersheet set is still located in the collate pocket 13 then the collator 1must wait until the earlier sheet set has been moved out of the collatepocket 13 before advancing sheet A1. When the collate pocket 13 is clearsheet A1 is fed into the collate pocket 13 and forms the first sheet insheet set A. The collate pocket stop 14 acts as a paperweight to retainthe sheets and the bounce stop 18 further assists in preventing thesheets from bouncing out of the collate pocket 13.

As described above, substantially simultaneously to the advancing ofsheet A1, the second hold point sensor 10 is checked and if the path isclear sheet A2 is transported to the second hold point 12, and likewisethe first hold point sensor 7 is checked and if clear sheet A3 isscanned and transported from the feeder 1 to the first hold point 9.This cycle continues, one step at a time, for each of sheets B1, B2 andB3 until they reach the collate pocket 13. For ease of understanding,the further description only refers to the steps from the second holdpoint 12 for each sheet.

From the barcode reading, the collator 2 knows that sheet A2 is part ofsheet set A and so in the next cycle sheet A2 is transported from thesecond hold point 12 to the collate pocket 13, on top of Sheet A1.Likewise, in the following cycle, Sheet A3 is fed from the second holdpoint 12 to the collate pocket 13, on top of Sheet A2, therebycompleting sheet set A.

Since the collator 2 knows that the next sheet held at the second holdpoint 12, sheet B1, is the first sheet in a new sheet set, the collator2 must wait until sheet set A is transported to a downstream device bythe output conveyor transport belt 16 and through the output rollers 19before allowing sheet B1 to be fed into the collate pocket 13. Since thecollator 2 will only begin transportation of sheet set A whenconfirmation is received that the receiving downstream device is clear,the collator 2 is forced to stop collating sheets until the downstreamdevice accepts sheet set A.

Once sheet set A has been transported to the downstream device, sheet B1is transported to the collate pocket 13, and in subsequent cycles sheetsB2 and B3 are stacked in top of sheet B1 to complete sheet set B, whichis then ready for transportation to the downstream device.

Only being able to collate one sheet set at a time can cause a delay inthe overall system, particularly when there are a large number of sheetsin each set, because once a blockage or bottleneck in the downstreamdevice is cleared and the sheet set is transported from the collatepocket 13, the collator 2 then must collate a whole new sheet set beforethe next sheet set is ready.

FIG. 2 shows an apparatus adapted according to the present inventionwhich reduces the problem described above by providing a buffer forcompleted sheet sets in the collator without increasing the footprint ofthe apparatus. Similar features are labelled with like-numberedreference numerals.

A sheet feeder 1 delivers consecutive sheets of paper to the collator 21and a barcode scanner 3 is positioned to scan each sheet as it travelsfrom the feeder to the collator 21. An upper conveyor transport belt 4and a lower conveyor transport belt 5 are arranged to transport thesheets to a first hold point 9, having an associated first hold pointsensor 7 and first hold point drive 8, and a second hold point 12,having an associated second hold point sensor 10 and second hold pointdrive 11 as described with reference to FIG. 1. A collate pocket 13, aspring loaded collate pocket stop 14 and a collate pocket sensor 15 arelocated downstream of the second hold point 12. A pair of output rollers19 and an output sensor 20 are located downstream of the collate pocket13. A first collate pocket eject pawl 22 a is positioned at one end ofthe collate pocket 13. The leading edge of each sheet fed into thecollate pocket 13 is stopped against a spring stop 14.

The first collate pocket eject pawl 22 a is part of a movable collatepocket eject device 23 which also comprises a second collate pocketeject pawl 22 b spaced equidistant from the first eject pawl 22 a on anouter surface of a collate pocket conveyor belt 24, which is driven by acollate pocket drive 25. When cycled, the collate pocket conveyor belt24 performs a half revolution which causes the first collate pocketeject pawl 22 a to travel substantially in the direction of the outputrollers 19, thereby pushing the collated sheet set towards the output.Because the two pawls 22 a, 22 b are spaced equidistant from each other,after the collate pocket conveyor belt 24 has performed a halfrevolution, the second pawl 22 b will be located in the same position asthe first pawl 22 a prior to the cycle, ready to drive out the nextdocument sheet set.

The collator 21 is designed to accept sheets of different lengths.Typically, the minimum document length accepted is approximately 89 mmand the maximum is approximately 406 mm. In order to ensure that theleading edge of the sheet stack, which is equivalent to the trailingedge of the individual sheets, always reaches the output rollers 19after the collate pocket conveyor belt 24 has been cycled. The collatepocket eject device 23 is adjustable along the plane of the conveyorbelts to accommodate different paper lengths. The eject stroke of thecollate pocket pawl belt 24 always moves the same amount to drive thesheet set to the output rollers 19. As little as 20-30 mm clearancebetween the sets of documents is necessary.

Provided the collator output is clear the collation will be continuous:there is no need to stop the apparatus unless a blockage occursdownstream.

The use of a stepper motor allows more accurate positioning of the pawlsand of conveyor belts and more accurate prediction of the position oftrailing and leading edges of sheets.

The operation of the apparatus according to the present invention willnow be described using the same example of collating two 3-sheet sets asused with reference to FIG. 1.

The operation of the collator 21 up to the point where the sheets areheld at the second hold point 12 is substantially identical to thatdescribed with reference to the collator 2 of FIG. 1, therefore thefollowing is a description of the stages after this point only.

Sheet A1 is held at the second hold point 12. Since sheet A1 has beenidentified by the barcode reader 3 as the first sheet in a set, thecollate pocket sensor 15 is checked to ensure that no earlier sheet setis located above the collate pocket conveyor belt 24 in the collatepocket 13. When the collate pocket sensor 15 indicates that thedownstream path is clear sheet A1 is fed into the collate pocket 13 andis stacked against the first collate pocket eject pawl 22 a to form thefirst sheet in sheet set A. In the next cycle sheet A2 is transportedfrom the second hold point 12 to sheet set A and in the following cyclesheet A3 is transported to the collate pocket 13, thereby completingsheet set A.

Once sheet set A is complete then collator 21 checks the status of theoutput sensor 20 to ensure that no earlier sheet set is waiting at theoutput. If the output is clear the collate pocket eject device 23performs one cycle. During the cycle, the first collate pocket ejectpawl 22 a pushes sheet set A downstream a distance less than the lengthof a sheet in the set, but far enough so that the leading edge of thesheet set engages the output rollers 19. Then a check is made todetermine if the receiving device downstream of the collator 21 is readyto accept sheet set A, and if so the apparatus activates the outputrollers 19 to transport sheet set A to the downstream device. If thedownstream device is not ready to accept sheet set A then the set isheld in position by the output rollers 19 until the downstream device isready, at which time sheet set A is transported to the downstream deviceby the output rollers 19.

As soon as the collate pocket conveyor belt 24 is free to eject the setbeing collated in the pocket and even while the last sheet of the set isarriving in the pocket, the collate pocket 13 is ready to accept thefirst sheet of sheet set B, even though sheet set A may still bepartially or completely located in the collate pocket 13. Sheet B1 istransported from the second hold point 12 to the collate pocket 13 andarrives at the spring stop 14 just after the trailing edge of sheet setA has moved forward under the action of the pawl.

If sheet set A is still located at the output of the collator when sheetB1 arrives at the collate pocket 13 then it is possible that sheet B1will partially overlay sheet set A. This does not cause a problembecause the movement of sheet set A is controlled by the output rollers19 and the resistive force exerted by the collate pocket stop 14prevents sheet set B from moving out of the collate pocket 13 when sheetset A is transported downstream. The collate pocket stop 14 may comprisea spring loaded ball as shown more clearly in FIG. 3. This holds sheetsin the collating position even when a previous sheet set is moving outof the collating position and might tend to displace the subsequentsheets by friction and allows closer tolerances and more overlap thusreducing the time intervals occurring between sheet sets being collated.It also prevents bounce back of sheets.

Sheets B2 and B3 are sequentially stacked in the collate pocket 13,thereby completing sheet set B. If, in the time it takes to collatesheet set B, the downstream device has accepted sheet set A, then theoutput sensor 20 will indicate that the output is empty and sheet set Bwill be advanced to the output rollers 19 by cycling the collate pocketeject device 23. Alternatively, if the downstream device has notaccepted sheet set A by the time sheet set B is complete then thecollator 21 will wait until sheet set A is accepted and transported outof the collator 21, after which sheet set B will be advanced to theoutput rollers 19 ready for transporting to the downstream device.

FIG. 3 shows an enlarged view of the collate pocket eject device 23 andshows a top sheet A3 of a first sheet set partially overlaid with thefirst sheet B of a second sheet set just after the first sheet A hasbeen moved out of the collating position by the first eject pawl 22 b.The sheet A1 is held in the collating position by the stop 14 whichcomprises a spring loaded ball 32 biasing the sheets toward the conveyorbelt 24 of the eject device 23. At this stage the second eject pawl 22 ais located behind the stop unit 14.

Whilst a document set is being collated the pawls (and belt 24) aregenerally stationary but when the last sheet of the second sheet set Bis being fed into the collating position the eject device begins to moveconveyor belt 24 and thus move pawl 22 a toward the stop unit 14 andsubsequently past the back stop to push sheet set B away from thecollating position. This timing can be controlled by a collatingposition sensor 15 detecting the presence or absence of sheets at thecollating position.

Alternatively or in addition the timing of the movement of the pawl 22 acan be controlled predictively by calculating when the last sheet willhit the back stop of stop unit 14 using information from the sheetscanner 3 about the number of sheets to be collated in each set and thespeed of the collator at any time. This allows the pawl to beaccelerated to reach full speed earlier and to eject the sheet sets morequickly than otherwise. The exit holding rollers will accelerate thesheet set away to allow the pawl to turn the corner as the eject devicecycles.

The eject device belt is driven by stepper motor 43 via drive belt 44.

The first sheet of any sheet set can be allowed to enter the collatingposition as soon as the pawl (22 a or b) moving the previous sheet setout of the collating position has cleared the horizontal position, i.e.gone below the level of the belt. This reduces the delay between eachcollation and speeds up the process.

Sensors and detectors can be arranged along the belts or in relevantpositions to determine the length of the sheet, and a control system canbe incorporated, for example to control the position of the collatepocket eject device in relation to the output rollers. Alternatively,the document length information may be incorporated into the machinecontrol data on each sheet which is read by the barcode scanner.

1. An apparatus for collating sheets, the apparatus comprising: acollating station having a collating position limited at its downstreamend by a stop member against which the sheets abut whilst they are beingcollated; means for conveying sheets to the collating position so as toform a collated sheet set comprising a predetermined number of stackedsheets; a collating station eject device for moving the collated sheetset away from the collating position to an exit position; and means forconveying the collated sheet set from the exit position out of theapparatus to a downstream sheet handling device; wherein the collatingstation eject device comprises at least one movable pawl arranged topush each collated sheet set away from the collating position to theexit position and wherein the apparatus is adapted to collate a secondsheet set at least partially overlying the first sheet set.
 2. Anapparatus according to claim 1 wherein the collating station ejectdevice and the exit conveying means are operable independently of eachother.
 3. An apparatus according to claim 1 wherein the exit conveyingmeans comprises a pair of holding rollers.
 4. An apparatus according toclaim 1 wherein the pawl is mounted on an outer surface of a belt, andfurther comprising means to drive the belt.
 5. An apparatus according toclaim 4 wherein the belt is an endless belt.
 6. An apparatus accordingto claim 5 comprising two pawls mounted at generally equidistantlyspaced intervals on the belt.
 7. An apparatus according to claim 1wherein the stop member is spring loaded.
 8. An apparatus according toclaim 7 wherein the stop member comprises a spring loaded ball.
 9. Anapparatus according to claim 1 wherein the location of the stop memberand the collating station eject device is adjustable depending on thelength of the sheets to be collated.
 10. An apparatus according to claim1 further comprising a sensor arranged to detect the presence of a sheetat the collating position.
 11. An apparatus according to claim 1 furthercomprising a sensor arranged to detect the presence of a sheet set atthe exit position.
 12. An apparatus according to claim 1 wherein themeans for determining sheet data for each sheet comprises a scannerarranged to read machine control data printed on sheets entering theapparatus.
 13. An apparatus according to claim 1 further comprising atleast one hold point upstream of the collating station.
 14. A method forcollating sheets comprising: conveying sheets to a collating position ina collating station so as to form a collated sheet set comprising apredetermined number of stacked sheets; ejecting the collated sheet setfrom the collating position by using a pawl to push it away from thecollating position to an exit position; at least beginning to form asecond collated sheet set in the collating position partiallyoverlapping the first sheet set in the exit position; and subsequentlyconveying the first collated sheet set out of the exit position to asheet handling device downstream of the apparatus when the downstreamdevice is ready.
 15. A method according to claim 14 wherein the movementof sheet sets from the collating position to the exit position isindependent of the movement of sheet sets from the exit position.
 16. Amethod according to claim 14 comprising sensing when a sheet is presentat the collating position.
 17. A method according to claim 14 wherein atleast the first sheet of the second sheet set is arranged to at leastpartially overlap the first sheet set in the collating position.
 18. Amethod according to claim 14 wherein the collating position is movablerelative to the exit position to accommodate different sizes of sheets.19. A method according to claim 14 comprising scanning the sheets formachine control data prior to transporting the sheets to the collatingstation.